Spinal correction surgery is used to correct spine deformities, disorders, or diseases, and otherwise stabilize the spine. Spinal correction surgery is sometimes needed to relieve pain or correct the alignment of a patient's spine. For example, spinal correction surgery is often used to treat spinal diseases, such as scoliosis and osteoarthritis, as well as degenerative disc diseases.
Pedicle screws are an integral part of most spinal correction surgeries. For example, a common surgery involves an internal fixation of the damaged or diseased vertebrae using a pedicle screw implant with a fixed link to a plate or a rod. A critical diameter for spinal surgery is thus the inner diameter of the pedicle of the vertebral body being treated. The inner diameter, however, can vary widely because it is directly related a person's height and the anatomy of each individual's cervical spine, thoracic and lumbar spine, and sacrum. Therefore, for a successful spinal surgery, the surgeon must be able to understand each patient's anatomical differences.
In most rod fixation systems, the pedicle screws are attached to a rod receiving head that is typically shaped like a tulip head for connecting to the rod. Although most systems provide a screw and rod receiving head combination that can articulate relative to one another, so that the tulip heads can align after the screws are inserted into the bone, it is nevertheless still difficult and time consuming to properly align a rigid rod into a pair of tulip heads. Compounding this problem is the surrounding tissue around the insertion area, which can be extremely tough to circumvent. The surgeon often has to exert a significant amount of force to spread apart the native tissue in order to properly seat the rod inside the tulip heads, thereby creating even more trauma to the injury site. With the additional challenges previously mentioned with proper pedicle screw insertion, there is a need for a better, more efficient rod fixation system for the spine.
Accordingly, it is desirable to provide a spinal fixation system that utilizes known techniques of rod stabilization with pedicle screws, but having the new feature of a self-cutting rod that has a cutting edge to quickly and easily insert in between the pedicle screws during implantation.